1. Field of the Invention
The present invention relates to a latch to be used for fixing a cover of a knapsack, bag or the like to its main body. More particularly, it relates to a twist latch wherein a knob attached to the main body is inserted into a hole portion formed in the cover from a back side thereof and then the knob appearing from the surface is twisted around so as to be fixed to the hole portion.
2. Description of the Related Art
FIG. 21 shows a conventional twist latch, disclosed in Japanese Utility Model Publication No. 5-3651. According to this invention, a main body 4xe2x80x2 is a rectangular box extended in its lateral direction whose bottom face is open. A square shaft-bearing portion 11xe2x80x2 in which a shaft 27xe2x80x2 of the knob 25xe2x80x2 is to be inserted is provided in a center of the main body 4xe2x80x2 and elastic pieces 52xe2x80x2 are disposed at a bottom end of the shaft-bearing portion 11xe2x80x2 so as to oppose each other. Then, a plate-like bottom portion 10xe2x80x2 extended in a lateral direction is provided at a bottom end of the main body 4xe2x80x2 and pair of leg portions 50xe2x80x2, 50xe2x80x2 are provided so as to protrude on the bottom face of the bottom portion 10xe2x80x2. A saw-tooth like engaging step portion 50axe2x80x2 is provided on an outer side face of each leg portion 50xe2x80x2. The knob 25xe2x80x2 has the protruding shaft 27xe2x80x2in a center of the bottom face thereof so as to be inserted into the shaft-bearing portion 11xe2x80x2. A plate 6xe2x80x2 is provided with through holes 32xe2x80x2 in which each of the leg portions 50xe2x80x2, 50xe2x80x2 is to be fitted from a back side of the main body 4xe2x80x2 and a pawl 51xe2x80x2 is provided so as to be protruded at each through hole 32xe2x80x2 so that it is capable of fitting to the engaging step portion 50axe2x80x2 of the leg portion 50xe2x80x2. The leg portions 50xe2x80x2, 50xe2x80x2 of the main body 4xe2x80x2 are inserted through a surface of a cloth and the plate 6xe2x80x2 is press-fit onto the leg portions 50xe2x80x2, 50xe2x80x2 from a back side of the cloth so that it is fixed thereto.
FIG. 22 shows another twist latch, which is disclosed in Japanese Utility Model Publication No. 5-4530. According to this twist latch, a main body of a plug 1xe2x80x3 has a shaft-bearing portion 11xe2x80x3 protruded upward in a center of a base 10xe2x80x3 of an ellipse shape, and an interior of the shaft-bearing portion 11xe2x80x3 is formed such that its upper side is of small diameter while its lower side is of large diameter. A through hole 55xe2x80x3 is formed on each of both the right and left sides of the base 10xe2x80x3. A rivet 54xe2x80x3 is inserted into each of the through holes 55xe2x80x3, while a cloth is nipped by the main body and a rear plate 60xe2x80x3 so that it is riveted. A knob body 5xe2x80x3 has a shaft portion 27xe2x80x3 provided in a center of a bottom of a rectangular knob 25xe2x80x3, and the shaft portion 27xe2x80x3 is divided into a cross shape so as to provide the shaft portion 27xe2x80x3 with elasticity. An expanded portion 29xe2x80x3 is provided at a tip of the shaft portion 27xe2x80x3. When it is inserted into a large diameter portion 22xe2x80x3 of the shaft-bearing portion 11xe2x80x3, the shaft portion 27xe2x80x3 is supported therein so as to be rotatable. Further, a corresponding socket 2xe2x80x3 has rivets 53xe2x80x3 protrudedly provided on both the right and left sides of the base 40xe2x80x3 containing a rectangular through hole 56xe2x80x3 through which the knob 25xe2x80x3 of the knob body 5xe2x80x3 can be inserted. This base 40xe2x80x3 is overlaid on a surface of a cloth and further a plate having rivet holes are overlaid on a back face of the cloth. Finally, with the cloth sandwiched, the rivets 53xe2x80x3 provided on the base 40xe2x80x3 are pressed and crushed to fix the cloth.
In the twist latch shown in FIG. 21 described above, a pair of the leg portions 50xe2x80x2, 50xe2x80x2 provided on a bottom face of the plug main body 4xe2x80x2 is inserted through the surface of the cloth such as a bag, and then, through holes 32xe2x80x2, 32xe2x80x2 of the plate 6xe2x80x2 are fit onto the leg portions 50xe2x80x2, 50xe2x80x2 existing on the back side of the cloth so as to mount the main body 4xe2x80x2 on the cloth. Therefore, if the plug main body 4xe2x80x2 is pulled strongly in a direction away from the surface of the cloth, the plug main body 4xe2x80x2 may be departed from the cloth easily when the plate is removed from the leg portions 50xe2x80x2, 50xe2x80x2 of the plug main body 4xe2x80x2, because there is no means for preventing a slip-out of the leg portions 50xe2x80x2, 50xe2x80x2 from the through holes 32xe2x80x2, 32xe2x80x2 except the engaging step portions 50axe2x80x2, 50axe2x80x2 formed on the leg portions 50xe2x80x2, 50xe2x80x2. Further, the leg portions 50xe2x80x2, 50xe2x80x2 may be protruded out of the plate 6xe2x80x2, thereby causing a problem that the protruded leg portions 50xe2x80x2, 50xe2x80x2 may catch contents of the bag.
In the twist latch shown in FIG. 22, the plug main body is set to the surface of a cloth such as a bag while the plate 60xe2x80x3 is placed on a back side of the cloth so as to nip the cloth. Then, the main body and the plate 60xe2x80x3 are fixed together with rivets 54xe2x80x3 so that the main body is fixed onto the cloth. Therefore, a quantity of components increases, which leads to increase of production cost, and inventory control of the components becomes complicated. Further, the attachment work using the rivets 53xe2x80x3, 54xe2x80x3 is troublesome.
The present invention has been achieved in views of the above-described problems. Therefore, an object of a first aspect of the present invention is to provide a plug of a twist latch ensuring safety because the plug is not protruded inside a bag and having a good appearance, bearing a long-term use and facilitating an attachment work thereof. For this purpose, a main body of the plug of the twist latch is inserted into a hole portion provided on a cloth such as a bag from a back side of the cloth and a fixing plate is fit to the plug main body appearing on the surface of the cloth from that surface, so that the plug main body can be attached firmly with stability to the cloth in a condition that it is fixed to the back side of the cloth.
Further, an object of a second aspect of the present invention is to provide a plug of a twist latch which facilitates attachment of the plug onto a cloth and insertion of the plug into a hole portion of a socket or fixing plate mounted to a cover.
Furthermore, an object of a third aspect of the present invention is to provide a plug of a twist latch which can be fixed firmly to a cloth by means of a simple mechanism and attached easily to adapt to a thickness of the cloth.
Still further, an object of a fourth aspect of the present invention is to provide a plug of a twist latch whose knob body can be attached to the main body easily and which has a knob portion having such a shape that facilitates gripping and operating thereof.
Still further, an object of a fifth aspect of the present invention is to provide a socket of a twist latch which can be engaged with the plug easily and fixed to a cloth in a stabilized condition by specifying a shape of the socket to correspond to the plug.
Still further, an object of a sixth aspect of the present invention is to provide a plug and a socket of a twist latch which allow the fixing plate to be engaged with the plug and socket easily so that the twist latch can be attached to a cloth easily.
Still further, an object of a seventh aspect of the present invention is to provide a fixing plate of a twist latch which can be commonly used for both the plug and the socket thereby realizing an effective attachment work.
Still further, an object of an eighth aspect of the present invention is to provide a plug and a socket of a twist latch having a structure capable of fixing the fixing plate to the plug and socket firmly in a stabilized condition.
Still further, an object of a ninth aspect of the present invention is to provide a fixing plate of a twist latch capable of achieving a firm fixing by specifying a shape of the fixing plate to be used for the plug and the socket.
Finally, an object of a tenth aspect of the present invention is to provide a plug and a socket of a twist latch which can be produced easily by limiting material to be used for the twist latch and whose recycling can be achieved.
To achieve the above objects, in order to firmly attach a twist latch to a cloth, such as a bag, by inserting the latch from a back side of the cloth, according to the first aspect of the present invention, there is provided a twist latch including a plug comprising: a main body having a cylindrical shaft-bearing portion protruded from a base; a knob body having a shaft portion containing a knob portion at an end portion thereof and adapted to be supported rotatably by said shaft-bearing portion; and a fixing plate adapted to be mounted onto and fit to an outer face of said shaft-bearing portion, wherein said shaft-bearing portion protruding from an upper face of the base has an engaging portion in an intermediate portion thereof, said fixing plate has a hole portion in which said shaft-bearing portion can be inserted, and said hole portion has fitting portions formed on a periphery thereof and adapted to be fit onto said engaging portion. Thus, the cloth can be nipped between the main body and the fixing plate by use of the shaft-bearing portion.
Further, according to the second aspect of the present invention, there is provided a twist latch wherein an outer peripheral face of the shaft-bearing portion of the main body of the plug is formed with a contracted diameter portion, whose diameter is smaller, extending from a top end to an intermediate portion of the shaft portion while an outer peripheral portion thereof extending from the intermediate portion to the base is formed with an expanded diameter portion, the engaging portion being formed at said expanded diameter portion on a side of a beginning end thereof.
Furthermore, according to the third aspect of the present invention, there is provided a twist latch wherein the engaging portion provided on the shaft-bearing portion of the main body of the plug is formed of several protruded ridge portions protruded from an outer peripheral face of the shaft-bearing portion and the fixing plate has tongue-like fitting portions in the periphery of the hole portion, which can be fit between the protruded ridge portions.
Still further, according to the fourth aspect of the present invention, there is provided a twist latch wherein the knob body of the plug is provided, a shaft portion is provided so as to protrude from a bottom face of the knob portion, the shaft portion is divided along its longitudinal direction by cross-like dividing grooves and has at its divided tip end an expanded head, cross-like convex rows to be protruded into the dividing grooves are formed in alignment with the dividing grooves on a bottom face of the knob portion, a through hole is provided inside the shaft-bearing portion of the main body such that a small-diameter hole is formed on an upper side and a large-diameter hole is formed on a lower side thereof, and cross-like concave grooves are provided in a top face of the shaft-bearing portion so as to coincide with the convex rows, wherein the shaft portion of the knob body is adapted to be inserted into the shaft-bearing portion so as to be intermittently rotatable therein.
Still further, according to the fifth aspect of the present invention, there is provided a twist latch wherein a socket corresponding to the plug has a cylindrical portion formed in a base of a main body thereof and having an inside diameter larger than an outside diameter of a contracted diameter portion of the shaft-bearing portion of the plug, several protruded ridge portions are provided on an outer peripheral surface of the cylindrical portion on a side of its top end so as to form an engaging portion, and a fixing plate is provided with tongue-like fitting portions formed in an inner periphery thereof and adapted to be fit onto said engaging portion.
Still further, according to the sixth aspect of the present invention, there is provided a twist latch wherein the engaging portion of the shaft-bearing portion of the main body of the plug and the engaging portion of the cylindrical portion of the main body of the socket are identical in shape, and each of the engaging portions is formed of several inclined faces on a side for inserting the fixing plate and several horizontal faces on a bottom thereof at a predetermined interval, respectively.
Still further, according to the seventh aspect of the present invention, there is provided a twist latch wherein the fixing plate for the plug and the fixing plate for the socket are identical in shape so that it can be commonly used for the plug and the socket.
Still further, according to the eighth aspect of the present invention, there is provided a twist latch wherein the shaft-bearing portion of the main body of the plug and the cylindrical portion of the main body of the socket has an ellipse cross sectional outer shape in order to facilitate stable fixing, and the engaging portion formed of several protruded ridge portions is respectively provided on an entire peripheral face of each of the shaft-bearing portion and the cylindrical portion so as to achieve firm fixing.
Still further, according to the ninth aspect of the present invention, wherein the periphery of the hole portion in the center of the fixing plate is formed with several cutout portions provided in the periphery of the hole portion of the fixing plate so as to form the tongue-like fitting portions so that it can perform resilient deformation easily.
Finally, according to the tenth aspect of the present invention, there is provided a twist latch wherein the main body, the knob body and the fixing plate of the plug and the main body of the socket are molded by injection molding or extrusion using thermoplastic resin.